title: The quasiparticle band structure of zincblende and rocksalt ZnO.
abstract: We present the quasiparticle band structure of ZnO in its zincblende (ZB) and rocksalt (RS) phases at the Γ point, calculated within the GW approximation. The effect of the p-d hybridization on the quasiparticle corrections to the band gap is discussed. We compare three systems, ZB-ZnO which shows strong p-d hybridization and has a direct band gap, RS-ZnO which is also hybridized but includes inversion symmetry and therefore has an indirect band gap, and ZB-ZnS which shows a weaker hybridization due to a change of the chemical species from oxygen to sulfur. The quasiparticle corrections are calculated with different numbers of valence electrons in the Zn pseudopotential. We find that the Zn(20+) pseudopotential is essential for the adequate treatment of the exchange interaction in the self-energy. The calculated GW band gaps are 2.47 eV and 4.27 eV respectively, for the ZB and RS phases. The ZB-ZnO band gap is underestimated compared to the experimental value of 3.27 by ∼ 0.8 eV. The RS-ZnO band gap compares well with the experimental value of 4.5 eV. The underestimation for ZB-ZnO is correlated with the strong p-d hybridization. The GW band gap for ZnS is 3.57 eV, compared to the experimental value of 3.8 eV.
authors.affiliation: CMT-group and EMAT, Departement Fysica, Universiteit Antwerpen, Groenenborgerlaan 171, B-2020 Antwerpen, Belgium. Hemant.Dixit@ua.ac.be
authors.forename: H
authors.initials: H
authors.lastname: Dixit
authors.forename: R
authors.initials: R
authors.lastname: Saniz
authors.forename: D
authors.initials: D
authors.lastname: Lamoen
authors.forename: B
authors.initials: B
authors.lastname: Partoens